Re: [PATCH -tip] compiler_types.h: Optimize __unqual_scalar_typeof compilation time

[Arnd Bergmann]

On Wed, May 27, 2020 at 1:36 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> On Wed, May 27, 2020 at 1:27 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > On Wed, May 27, 2020 at 12:33 PM Marco Elver <elver@xxxxxxxxxx> wrote:
> >
> > This gives us back 80% of the performance drop on clang, and 50%
> > of the drop I saw with gcc, compared to current mainline.
> >
> > Tested-by: Arnd Bergmann <arnd@xxxxxxxx>
> >
>
> Hi Arnd,
>
> with "mainline" you mean Linux-next aka Linux v5.8 - not v5.7?

I meant v5.7.

> I have not seen __unqual_scalar_typeof(x) in compiler_types.h in Linux v5.7.
>
> Is there a speedup benefit also for Linux v5.7?
> Which patches do I need?

v5.7-rc is the baseline and is the fastest I currently see. On certain files,
I saw an intermittent 10x slowdown that was already fixed earlier, now
linux-next
is more like 2x slowdown for me and 1.2x with this patch on top, so we're
almost back to the speed of linux-5.7.

      Arnd